SOLUTION: Solve the system of equations using the substitution method. If the answer is a unique solution, present it as an ordered pair: (x, y). If not, specify whether the answer is “no

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Question 40814This question is from textbook INTERMEDIATE ALGEBRA
: Solve the system of equations using the substitution method.
If the answer is a unique solution, present it as an ordered pair: (x, y). If not, specify whether the answer is “no solution” or “infinitely many solutions.”
3x + y = 7
4x – y = 21
 This question is from textbook INTERMEDIATE ALGEBRA

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
3x + y = 7
4x – y = 21

Add the two equations to get:
7x=28
x=4
Substitute that value into either of the original equations
to solve for "y".
3(4)+y=7
y=-5
Solution: x=4, y=-5
Cheers,
Stan H.